| Summary: | 博士 === 國立中興大學 === 昆蟲學系所 === 106 === The cotton aphid, Aphis gossypii (Glover), is a major pest of many crops worldwide and a major cucumber plant pest in Taiwan. Because cotton aphid rapidly develop insecticide resistance and because of the insecticide residue problem, a safe and sustainable method is required to replace conventional insecticide control methods. Methyl salicylate , a herbivore-induced plant volatile, has been shown to affect aphids’ behavior and attract the natural enemies of aphids for reducing their population. Therefore, methyl salicylate was first field-tested for the effectiveness of attracting natural enemies in Agricultural Research Institute. Then, this study evaluated the direct effects of methyl salicylate on cotton aphids’ settlement, reproduction, nymph developmental time, population development, and attractiveness to natural enemies. The efficiency of using methyl salicylate and the commercial insecticide pymetrozine for reducing the cotton aphid population in laboratory and outdoor cucumber plant pot was also examined. The results showed that yellow sticky paper baited with methyl salicylate significantly attracted more Scymnus Pullus sodalis Weise, Scymnus Pullus quadrillum Motschulsky, brown lacewing, Orius strigicollis Poppius, Cardiastethus exiguus Poppius and Campylomma chinesis Schuh than control and the attractions were different followed by different concentrations. There were no difference in winged aphids’ settlement, reproduction, nymph developmental time and population development between the methyl salicylate treatment and control. Cucumber plants infested with cotton aphid and baited with 0.1% methyl salicylate contained significantly higher numbers of the natural enemy of cotton aphid, namely S. sodalis. Furthermore, methyl salicylate-treated cucumber plants contained a lower number of cotton aphid. Significantly lower cotton aphid numbers were found on cucumber plants within a 10-m distance of methyl salicylate application. In addition, fruit yield showed no difference between the methyl salicylate and pymetrozine treatments. According to our findings, under our tests condition, 0.1% methyl salicylate application can replace insecticides as a cotton aphid control tool. However, large-scale experiments are necessary to confirm its efficiency and related conservation biological control strategies before further use.
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